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Phil Jones Bass Briefcase PJB - Batteries

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Howdy all,

I'm probably going to do some fun busking in the summer months with some friends - and I plan on using my PJB amp taking use of the battery facility.

What i'd like to know is where you get these batteries from and what types/makes you can use (all the links on the web are for American sites).

Also, how long should each charge last for with a medium to high volume use.

Also, :) how do you charge the battery and could you connect up a spare external battery without disconnecting the internal battery :huh: ???

Thank Q

And Happy Easter all

Greg ;)

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[quote name='The Funk' post='162011' date='Mar 22 2008, 11:49 PM']I thought it ran off car batteries. I may be wrong![/quote]


I've got this amp and I have a battery in it... I got mine from Maplins! I'm not entirely sure what batery it is now - it was about a year ago I did it - but I can take it out and have a look. I've found you can get about 1 hour max out of the battery before it slowly dies on you...

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[quote name='five-string.co.uk' post='161913' date='Mar 22 2008, 06:56 PM']What i'd like to know is where you get these batteries from and what types/makes you can use (all the links on the web are for American sites).

Also, how long should each charge last for with a medium to high volume use.

Also, :) how do you charge the battery and could you connect up a spare external battery without disconnecting the internal battery :huh: ???[/quote]

You need to read the owners manual (also available on the website) and make a note of the battery types. You need a sealed lead-acid battery of the right size with the right connectors but any equivalent will do - if there's a PowerSonic battery listed then you'll probably easily find those in the UK and there is more than likely a Yuasa/Genesis equivalent.

Then you ring up your local battery specialist - ours is www.combatalexander.co.uk - and ask for an equivalent. Not sure whether you need a charger or whether the pjb will charge up an internal battery if you plug it into the mains. Once again the manual is your friend.

Run time will depend on the current drawn by the amp and the size of the battery - if they've used a 12V 10 amp hour battery and the amp draws 2.5a, it'll run for 4 hours on a charge. 12V would be a sensible choice which would allow you to use an external car battery which will run much longer but be a PITA to cart around.

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[quote name='pete.young' post='162717' date='Mar 24 2008, 04:58 PM']Run time will depend on the current drawn by the amp and the size of the battery - if they've used a 12V 10 amp hour battery and the amp draws 2.5a, it'll run for 4 hours on a charge. 12V would be a sensible choice which would allow you to use an external car battery which will run much longer but be a PITA to cart around.[/quote]
As it's 12V, it also allows you to use motorcycle batteries, which are generally smaller and lighter than car batteries. They've got a 7.2Ah battery as the option which gives 1 hour's use. They'll probably cost more, Ah for Ah, than car batteries though.

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Car batteries don't last long in this sort of application, as they're designed for high current drain and long charge cycles. What you need are deep cycle batteries, as used in wheelchairs, golf buggies etc. They're designed to be run right down over a period of time, then recharged. A good deep cycle battery will discharge/recharge over 1000 times if cared for properly, whereas the best car batteries only survive a couple of hundred cycles when used like this.

Andy

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Just a quick additional thought (not battery related!)

[i]Assuming[/i] that you're going to be outside or in a relatively open space, it may be advantageous to back the PJB up against a wall/large solid object, or better still, in a corner.

It'll give a useful boost to the bottom end without pushing the amp harder by EQing it in, and you can control it by moving the amp around a bit.
I find that the LF often disappears in big open spaces...
Unless you've got a festival's worth of 1M Watt PA!

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Thanks for all your advice chaps.

I've managed to get a suitable battery from these guys [url="http://www.barden-uk.com/"]http://www.barden-uk.com/[/url] for less than £15 which is good (I think?) and they were just up the road from me too!! Think they do mail order if anyone else is interested.

The battery fitted well - nice and snug so won't rattle about and works just fine.

It does charge up when the amp is plugged in, even if the power switch on the front is swithed off.

I can also see this amp serving me well for jam nights too - no need to fight over one or two plug sockets on stage!!! :)

[u][b]ONE LAST QUESTION FOR ANY ELECTRICIANS:[/b][/u]

With the battery connected internally, if this runs flat, can I connect an external battery to the exterior metal contacts on the back of the amp, or will this connecting of two batteries be; bad news / blow up / damage the amp / damage the batterys?

Greg

Edited by five-string.co.uk

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On 26/03/2008 at 11:44, five-string.co.uk said:

I've managed to get a suitable battery from these guys http://www.barden-uk.com/ for less than £15 which is good (I think?) and they were just up the road from me too!!

ONE LAST QUESTION FOR ANY ELECTRICIANS:

With the battery connected internally, if this runs flat, can I connect an external battery to the exterior metal contacts on the back of the amp, or will this connecting of two batteries be; bad news / blow up / damage the amp / damage the batterys?
 

Greg... did you ever find an answer to this question? How’s the PJBriefcase holding up after all these years?

I’m going to do some busking so I’d probably like to have a spare battery on hand.

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If you connect two batteries in parallel (as you're suggesting) the battery with the higher voltage will try charge the battery with the lower voltage, as well as powering your amp.  Not a good idea if you want to conserve power for busking.

It would be better to disconnect the discharged battery and connect the charged one in its place.

Also, for long battery life, don't discharge your batteries under about 50%, or about 12.4 volts, (depending on the type of battery - check makers figures).

Frank.

Edited by machinehead
punctuation

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4 hours ago, machinehead said:

If you connect two batteries in parallel (as you're suggesting) the battery with the higher voltage will try charge the battery with the lower voltage, as well as powering your amp.  Not a good idea if you want to conserve power for busking.

It would be better to disconnect the discharged battery and connect the charged one in its place.

Also, for long battery life, don't discharge your batteries under about 50%, or about 12.4 volts, (depending on the type of battery - check makers figures).

Frank.

Thank you. Good knowledge. Good logic. Thank you.

Joe

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Does that not depend on what battery type it is (lead-acid, NiCad, NiMh, etc)? I thought the opposite was true for the type of battery that comes with modern mobile phones (and portable battery packs for bass amps!) that it was recommended to fully discharge / charge every now and then rather than regularly topping up a partially discharged battery? 

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2 hours ago, dannybuoy said:

Does that not depend on what battery type it is (lead-acid, NiCad, NiMh, etc)? I thought the opposite was true for the type of battery that comes with modern mobile phones (and portable battery packs for bass amps!) that it was recommended to fully discharge / charge every now and then rather than regularly topping up a partially discharged battery? 

The recommended battery type for the PJBriefase is a Sealed Lead Acid Gel.

According to what I’ve been reading... there’s no blanket answer to the question about discharge levels for all lead-acid-gel battery cells (unless I’ve totally misunderstood). Some boast a full discharge is possible, while others say it’s best to only discharge around halfway to get the most cycles. But how would you know what halfway was when you’re midway through your busking blues jam? :facepalm:xD

Without taking your voltmeter out with you, I guess you’d have to charge it to full, then run it completely flat with a stopwatch to time it. Then you’d know what halfway was in time. Even that wouldn’t work because it depends what you’re playing (lower notes take more battery power right?), how loud the amp is set and several other factors to do with things I don’t want to understand... it’s far too complicated. I just want to play my bleedun bass!!! :dash1:

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They recommend a laptop battery for the Double Four. I guess car batteries are meant to be continually run at close to full charge so are perhaps not the best choice for a bass amp then!

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10 minutes ago, dannybuoy said:

They recommend a laptop battery for the Double Four. I guess car batteries are meant to be continually run at close to full charge so are perhaps not the best choice for a bass amp then!

Yes that’s exactly what I’ve learned. An automotive battery will work, but as you say they are not designed to be discharged.

Hopefully a couple of these from Screwfix will do the trick... https://www.screwfix.com/p/sealed-lead-acid-battery-12v-7ah-100-x-65-x-151mm/38315?tc=WA3&ds_kid=92700024372740006&ds_rl=1248181&ds_rl=1245250&ds_rl=1249481&gclid=EAIaIQobChMI2tegqayz2gIVir_tCh3uDwKBEAQYASABEgJPmvD_BwE&gclsrc=aw.ds&dclid=CLPv48-ts9oCFZfhGwodRxsBCA

one as a spare for when the other is at 50% hahahhaha

Edited by Jumanji

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2 hours ago, Jumanji said:

The recommended battery type for the PJBriefase is a Sealed Lead Acid Gel.

According to what I’ve been reading... there’s no blanket answer to the question about discharge levels for all lead-acid-gel battery cells (unless I’ve totally misunderstood). Some boast a full discharge is possible, while others say it’s best to only discharge around halfway to get the most cycles. But how would you know what halfway was when you’re midway through your busking blues jam? :facepalm:xD

Without taking your voltmeter out with you, I guess you’d have to charge it to full, then run it completely flat with a stopwatch to time it. Then you’d know what halfway was in time. Even that wouldn’t work because it depends what you’re playing (lower notes take more battery power right?), how loud the amp is set and several other factors to do with things I don’t want to understand... it’s far too complicated. I just want to play my bleedun bass!!! :dash1:

Don't believe what you read from manufacturers.  All lead acid batteries will die very quickly if regularly fully discharged. And yes, including the ones sold as "leisure batteries". (Proper traction batteries excepted, but they cost around £800+ so not even considered here.)

Car starting batteries can die after as few as 30 full discharges on the cheaper ones.

@Jumanji Even that battery you bought shouldn't be discharged more than circa 50% for a longer life.  It will die very quickly if you flatten it on each use.

Frank.

 

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16 minutes ago, machinehead said:

Don't believe what you read from manufacturers.  All lead acid batteries will die very quickly if regularly fully discharged. And yes, including the ones sold as "leisure batteries". (Proper traction batteries excepted, but they cost around £800+ so not even considered here.)

Car starting batteries can die after as few as 30 full discharges on the cheaper ones.

@Jumanji Even that battery you bought shouldn't be discharged more than circa 50% for a longer life.  It will die very quickly if you flatten it on each use.

Frank.

 

Thanks Frank. That’s what I need, a definitive answer!

I haven’t bought any batteries yet. Still researching, and have messaged PJB to ask for recommended UK battery suppliers. They have a list for US companies in the instruction manual, but not for UK suppliers.

Joe

ps. This wasn’t my topic originally. I was just hoping to find out how to connect an external battery without having to turn the thing over, unscrew the battery plate, remove the dead (50% depleted) battery, etc etc

I’m getting closer to answers 

Edited by Jumanji

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